Production Machining

APR 2017

Production Machining - Your access to the precision machining industrial buyer.

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Page 22 of 91 :: 21 Helping Precision Machine Shops Be More ProducƟ ve and Profi table Technical Regulatory Management Quality Technical Regulatory Management Quality Craftsman's Cribsheet Miles Free – Director of Technology and Industry Research NUMBER 53 Unleaded brasses are not necessarily harder to run than leaded brass. They are just different. By recognizing and accommodating for their lack of lead, and the resultant different thermal conductivity, differences in chip forming and the need to up-tool for heavier feeds rather than higher speeds, your shop can be successful at making parts from these newer, more challenging grades. What are some strategies for machining the unleaded brasses? • Increase the feed. Since we lost the lead and the ability to run at higher speeds, increasing the feed can help us get to equivalent cubic inches of removal rates. • Improve the machine rigidity. Heavier feeds mean the machine needs to be adjusted and sol- id. It also means more horsepower required, again mandating a rock-solid setup. • Improve the tool. Even 4 percent lead is very forgiving of tool quality; the nonleaded grades are the opposite, they present a number of challenges to your tools. Improved materials, geometry and coatings are key to machining unleaded brasses with minimum issues. They will require fewer replacements, helping to get more net production at the end of the shift. Unleaded Brass: Change Your Thinking • Improve the chip management. Some unlead- ed grades replace the lead with zinc, resulting in a grade with a type III chip, stringy and birds-nest prone. With these grades, pay attention to drills selected, and try inserts with chip control featres to help you manage that chip. • Deal with the increased heat. The lead helped to reduce friction and heat in the leaded grades. With the lead removed, you will have increased heat generated. Carbide is more forgiving of heat, as are tool coatings. Talk to your supplier of metalworking fl uids; chances are, it will have a fl uid that will help manage those extra BTUs and maintain your tools' edges. • Change your ideas about machining brass. Unleaded brass machines more like steel than brass. As long as you think of it like leaded brass, you will fi ght it. Instead, think of it as just a yellow version of 1215 steel or stainless and your expec- tations will be much closer to reality. The market for precision machined parts continues to evolve. Evolve your thinking and processing to adjust to the realities of unleaded materials to re- main a viable and preferred supplier. 12L14 (with Lead) 1215 (without Lead) COPING STRATEGY (Going from 12L14 to 1215) RESULT SPEEDS HIGHER LOWER Reduce speeds; increase feeds concurrently Same/similar cubic inches removal; less heat TOOL WEAR REDUCED INCREASED Faster/easier to replace tooling; Higher grade tools; improve coat- ings, increase back rake angle Increase tool life; increase uptime/ day; generate less heat CUTTING TEMPERATURE LOWER HIGHER Improve coolant; improve coolant delivery Increase tool life; increase uptime/day CHIP-TOOL CONTACT AREA SMALLER LARGER Rethink cutting strategy Reduce chip thickness DRILL CHIPS THINNER THICKER Drills – Oilhole; pecking Expedient removal of chips & heat OD TOOL CHIPS SHORTER LONGER Adjust angles; add chipbreakers Control chips SURFACE FINISH BEST WORSE Change tools more often; SPC to determine when Maintain acceptable fi nish; Reduce downtime/day THE SHOPFLOOR CHEAT SHEET All Craftsman's Cribsheets are available for viewing and download at

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